Generally, a washing machine with a drying function is a home appliance that can wash and dry laundry.
The washing machine with the drying function is classified into an exhaust type in which air in the drum is exhausted to an external side during a drying process and a condensing type in which air in the drum is not exhausted but circulated in the washing machine.
The condensing type washing machine includes a drying duct provided on an upper portion of a tub and a heater installed in the drying duct. The heater heats air introduced into the drum to a high temperature. A condensing duct for connecting the drying duct to the tub enclosing the drum is provided to lower the temperature of the air exhausted from the drum. The air passing through the condensing duct is returned into the drying duct. The air is changed into a high temperature/dry state in the drying duct and directed into the drum. This circulation process is repeated.
Meanwhile, when electric power is applied to the heater installed in the drying duct, the heater generates heat above 700° C. and thus the air maintains a temperature of about 120° C.
Therefore, the drying duct is generally formed of metal material endurable the high temperature. For example, the drying duct is formed of aluminum through a die-casting process.
However, when the drying duct is formed of the aluminum through the die-casting process, the manufacturing cost increases and an overall weight of the drum-type washing machine increases.
Furthermore, since a cabinet on which front and rear surfaces of the drying duct are supported requires a rigidity enough to endure the load of the drying duct. This also cases the increase of the manufacturing cost of the washing machine.
In addition, when the drying duct is formed of the aluminum through the die-casting process, a thickness of the drying duct increases and thus an overall volume of the washing machine increases or an internal space of the drying duct is reduced.